Long: http0.9 Tags: Versions Protocols: HTTP Added: Help: Allow HTTP 0.9 responses --- Tells curl to be fine with HTTP version 0.9 response. HTTP/0.9 is a completely headerless response and therefore you can also connect with this to non-HTTP servers and still get a response since curl will simply transparently downgrade - if allowed. Since curl 7.66.0, HTTP/0.9 is disabled by default.